The vegetative roof will be divided into three sections designed to test different aspects of green roof design, including materials and soil depth. The remaining 52,000 square feet of the roof will use a white membrane material, and will also be monitored, allowing comparisons of factors including surface temperature, water flow and building operations.

PSU’s Green Building Research Laboratory will deploy sensors and a weather station, and the city’s Bureau of Environmental Services will measure stormwater runoff, while consulting firm the Cadmus Group will monitor the performance of rooftop air conditioning units, and the Audubon Society will conduct bird count surveys.

Lab director David Sailor said the data will help the green building industry, but it will surely help Walmart as well. Not only will the project compare the store’s white and green roof sections, but it will compare this data to similar metrics from a Walmart green roof in Chicago.